The invention relates to dry shavers having a cutter blade and co-operating shear blade arrangement. The invention relates at least both to electric dry shavers of the type having a reciprocating cutter and a shear blade arrangement in the form of a perforated foil with a plurality of perforations, and also to dry shavers of the type having a rotary cutter member or blade underlying an external shear member provided with apertures for entry of the hairs to be cut. The invention also relates to cutter blade assemblies for such dry shavers.
The history of shaving to date has been the search for the ever-closer shave. However, certain skin and hair types develop “shaving bumps” or pseudofolliculitis barbae (PFB) in certain areas of the beard when a close shave is effected. This can occur where obliquely exiting hairs are cut tangentially too close to the skin surface causing them to re-enter into the skin where they may occasion inflammation. In shaving close, certain skin and hair types thus experience or develop inflammation due to re-entry into the skin of the closely shaved hairs.
U.S. Pat. No. 4,003,390 discloses the use of apertured guides or spacers between the razor head and the skin in order to cut or trim hairs at a predetermined distance from the skin.
U.S. Pat. No. 5,867,908 describes a rotary razor external cutting member having apertures of varying width in order to cut longer and shorter hairs more effectively and with less irritation, but ultimately achieving a “close” shave.
International Published Patent Application No. WO 98/35794 describes different shaving fields provided on an external cutting member, oriented in a fashion so that the longer hairs are cut first, or pre-shaved, by the outside fields before being properly close shaved by the inside fields.
European Patent No. 1 231 034 granted to the current applicant describes a rotary razor giving a variable height of cut, a specific embodiment of such envisaged using interchangeable shaving heads of different thicknesses and, in a further embodiment, a double shaving head containing an outer displaceable “dummy” shield so as to achieve a variable height of cut.
EP 1 231 034 also relates to a dry shaver having a variable thickness moveably shear foil mounted in a shaver head. An adjustment mechanism is provided to allow the user to select the required length of shave.
It is believed that none of the above razors and shavers completely addresses the inflammation problem discussed above. Accordingly, it would be desirable to provide a cutter blade assembly and dry shaver directed to overcoming the inflammation problems discussed hereinabove. It would further be desirable to provide a cutter blade assembly directed to achieving a variable height of cut by varying the thickness of the shear blade so as to achieve selectively a short or a long hair shave by using the same shear blade. In addition, it would be desirable to provide a rotary dry shaver which allows for a close shave in certain areas and a “longer” shave in other areas. Still further, it would be desirable to provide a dry shaver unit having an elongate flexible shear foil which allows for a variable height of cut.